The Science of Medical Marijuana: What’s the Latest?

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Scientists gathered at the annual meeting of the American Association for the Advancement of Science to talk shop on medical marijuana.

To
date, nearly half of the states in the U.S.
have legalized medical marijuana.

However,
because the drug remains illegal at the federal level, the Food and Drug
Administration (FDA) has not regulated it.

This
leaves medical users to navigate treatment on their own. The issue was a prime
topic at the annual meeting of the American Association for the Advancement of
Science this week in San Jose, California.

Humans
have used cannabis for thousands of years. But only in the past few decades
have scientists begun to understand how the wide range of chemicals found in
cannabis work in the body.

“We’re in much better shape now than we ever have been to
know exactly what’s in there, so we can have cannabis that’s quantified in
terms of the major psychoactive ingredients,” explained Mark Ware, director of clinical
research at the Alan Edwards Pain Management Unit at the McGill University
Health Centre, in an interview with Healthline.

What, Exactly, Is in Marijuana?

Among
these ingredients are at least 104 active cannabinoids. They mimic the actions
of signaling chemicals in the brain called endocannabinoids, which dock with
specific receptors on the surface of cells. Some cannabinoids also dock with
other receptors, including those for serotonin and adrenaline.

The
most famous of these chemicals is delta-9-tetrahydrocannabinol
(THC), which is largely responsible for cannabis’ intoxicating effects.

Meet the Cannabinoids

delta-9-tetrahydrocannabinol (THC)

tetrahydrocannabivarin (THCV)

cannabigerol (CBG)

cannabidiol (CBD)

cannabidiolic acid (CBDA)

Each
chemical acts on different receptors in different ways.

For
example, THCV blocks the mind-altering effects of THC while simultaneously
combatting inflammation in the body, which may help relieve symptoms of Parkinson’s disease and protect against liver damage. It also changes how
the serotonin receptor behaves during psychosis, potentially offering a
treatment for schizophrenia.

Meanwhile,
CBG’s unique profile of activity at adrenaline and serotonin receptors makes it
a prime candidate for treating pain.

CBD
and CBDA, on the other hand, are better candidates to treat nausea.

Other
possible uses of cannabinoids include treating stroke, PTSD, epilepsy, and even
drug addiction itself.

Other Compounds Found in Marijuana

Cannabis
also contains at least 400 other compounds, such as terpenes, limonenes, and
flavonoids. Also found in scented herbs like thyme and oregano, these aromatic
compounds are what give the different strains of marijuana their distinctive
colors, tastes, and scents.

Ware
explained that these compounds may also have anti-inflammatory, anti-seizure,
and possibly even pain-killing effects.

Eventually,
patients seeking relief may have access to a wide range of FDA-approved
medications, each with the right combination of compounds to treat their
specific symptom set.

These
cocktails could be more effective than the currently FDA-approved,
THC-mimicking, dronabinol (Marinol). Marinol has failed to displace medical
cannabis despite being available to treat nausea and other conditions since
1985.

Another
drug derivative is nabiximols (Sativex), a blend of THC and CBD for multiple
sclerosis patients.

For chronic pain management nowadays, it’s rare that I have patients that leave my clinic on one single drug.

Mark Ware, McGill University Health Centre

Drug mixtures should come as no surprise to those
experienced with major medical conditions.

“For chronic pain management nowadays, it’s rare that I have
patients that leave my clinic on one single drug,” Ware explained. “They need
several different agents that all act on slightly different receptors, and the
right combination of those drugs helps alleviate the pain to allow them to
improve their functioning and quality of life. I think cannabis is probably the
same way — it’s not one ingredient; it’s multiple, each of which works on
slightly different receptors. I think the challenge is trying to figure out
what is that correct combination of receptor targets.”

Herbal Solutions Are an Option

Such
drugs will take decades to develop and reach the market. Until then, patients have
herbal cannabis as an option.

However,
there are dozens of strains of cannabis on the market, each claiming to have
different properties for treating different symptoms.

Cannabis
suppliers also often have a hard time controlling the quality of their product,
meaning that two batches of the same strain could vary in potency and chemical
composition.

We’ve got thousands of patients who’ve been using marijuana now in some kind of legal regime for dozens of years … we could be learning from that interaction between patient and plant to see: Are there some combinations of cannabinoids that are better for certain symptoms than others?

“We’ve
got thousands of patients who’ve been using marijuana now in some kind of legal
regime for dozens of years, and nobody’s ever tracked these patients over
time,” he said. “We have learned nothing in terms of safety or why they’re
using it. We could track the patients, we could map the patients’ [symptoms]
with the particular cannabis that they’re using, and we could be learning from
that interaction between patient and plant to see: Are there some combinations
of cannabinoids that are better for certain syndromes and symptoms than
others?”

Cannabis,
however, isn’t without risk. Certain groups should avoid using the drug,
including:

people with a family
history of schizophrenia or psychosis: Cannabis may activate a latent
predisposition for mental illness.

people under the age of
25: Cannabis may interfere with how the brain matures during adolescence and
young adulthood.

people who are driving,
especially those who have consumed alcohol: Even small amounts of alcohol and
cannabis can amplify one another’s effects, drastically increasing the rate of driving
mistakes.

However,
beyond these risks, the majority of studies examining the dangers of cannabis
have found no long-term effects after a month of nonuse. This includes a study published earlier this year showing that cannabis
use does not change the volume or shape of important parts of the brain.

Either
way, the question of medical cannabis isn’t whether using the drug is more
dangerous than abstinence. The question is whether cannabis can provide more
effective symptom relief, with fewer side effects, than existing medications.

“The
message here is not that cannabis is useful for everybody, it’s that for those
severely affected people it may be an option,” said Ware. “You want a clean,
healthy brain that’s wiring up properly. You want a clean, healthy fetus. You
want clean, healthy drivers. It’s just common sense.”